Lysozymes are a family of enzymes that catalyze the hydrolysis of certain mucopolysaccharides of bacterial cell walls, specifically the beta (1-4) glycosidic linkages between N-acetylmuramic acid and N-acetylglucosamine, and causes bacterial lysis. Lysozymes occur in diverse organisms including viruses, birds, and mammals. In humans, lysozymes are found in spleen, lung, kidney, leucocyte, plasma, saliva, milk, tears, and cartilage. (Online Mendelian Inheritance in Man (OMIM) #153450 Lysozyme; Weaver, L. H. et al. (1985) J. Mol. Biol. 184:739-741.)
The two known isoforms of lysozymes, chicken-type (C-type) and goose-type (G-type), were originally isolated from egg white of chicken and goose egg white, respectively. Chicken and goose-type lysozymes are similar in three-dimensional structures but different in amino acid sequences. (Nakano, T. and Graf, T. (1991) Biochim. Biophys. Acta 1090:273-276.) In chickens both isoforms of lysozyme are found in neutrophil granulocytes, but chicken-type lysozyme is found only in egg white. An analysis of the expression pattern of chicken-type and goose-type lysozyme mRNA in chicken tissues was performed. Chicken-type lysozyme mRNA is found in both adherent monocytes and macrophages and nonadherent promyelocytes and granulocytes as well as cells of the bone marrow, spleen, bursa, and oviduct. Goose-type lysozyme mRNA is found in non-adherent cells of the bone marrow and lung. The goose-type lysozyme gene cloned from chicken encodes a 211 amino acid protein containing a putative 26 amino acid N-terminal cleavable signal sequence. Homologous goose-type lysozymes are found in chicken, black swan, goose, and ostrich. Conserved residues include the three catalytic center residues Glu99, Asp112, and Asp123 (numbering from the chicken goose-type lysozyme precursor) and four cysteines that are known to form two disulfide bonds in the black swan goose-type lysozyme. Several lsozymes have been found in rabbits, including leukocytic, gastrointestinal, and possibly lymphoepithelial forms. (OMIM #153450, supra; Nakano (1991) supra; and GenBank g1310929.) A human lysozyme gene has been cloned that encodes a protein that is similar to chicken-type lysozyme. (Yoshimura, K. et al. (1988) Biochem. Biophys. Res. Commun. 150:794-801.) Lysozymes have been approved to associated with human diseases. Nakano (supra) suggested a role for lysozyme in host defense systems. Older rabbits with an inherited lysozyme deficiency show increased susceptibility to infections, especially subcutaneous abscesses. (OMIM #153450, supra.) Human lysozyme gene mutations cause hereditary systemic amyloidosis, a rare autosomal dominant disease in which amyloid deposits form in the viscera of important organs, including the kidney, adrenal glands, spleen, and liver. This disease is usually fatal by the fifth decade. The amyloid deposits contain lysozyme with amino-acid substitutions. Renal amyloidosis is the most common and potentially the most serious form of organ involvement. (Pepys, M. B. et al. 1993 Nature 362:553-557; OMIM #105200 Familial Visceral Amyloidosis; Cotran, R. S. et al. 1994 Robbins Pathologic Basis of Disease, W.B. Saunders Company, Philadelphia, Pa., pp. 231-238.) Goose-type lysozyme is expressed in avian promyelocytes transformed with avian myeloblastosis virus containing the L106 mutant form of the v-myb oncogene. (Nakano, T. and Graf. T. (1992) Oncogene 7:527-534; and Nakano 1991 supra.)
Therefore, it is a long need in the art to develop new lysozyme.